I think you might be missing a few steps here. "Plug it in" to what? What will be processing the sound of the pad or pedal into an audible thing? Where will the playback come from? Might be easier/better off trying to use one of the other "pads" from rockband kit, but I don't know much about them. Assume they are like most e-drums.

+1 to this. You still need a module (or something) to run the trigger. Even if you could get it to work, those Rockband pedals don't exactly offer the best action/ response (fine if you're just playing basic beats though I suppose).